body {
    margin: 0;
    padding: 0;
}

#container {
    height: 100vh;
}

.bg {
    position: absolute;
    width: 100%;
    height: 100%;
}

.sun {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    width: 600px;
    height: 600px;
    background-color: orange;
    border-radius: 50%;
}

.moon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(calc(-50% + -160px), calc(-50% + -180px));
    width: 600px;
    height: 600px;
    box-shadow: 160px 180px 0 cyan;
    border-radius: 50%;
}

.sea {
    position: absolute;
    bottom: 0;
    width: 100%;
    height: 35%;
    backdrop-filter: blur(100px);
    -webkit-backdrop-filter: blur(100px);
    z-index: 100;
}

.sun-box,
.moon-box,
.bg {
    transition: 1s ease-in-out;
}

.sun-box,
.moon-box {
    position: relative;
    overflow: hidden;
}

.light .sun-box {
    height: 100%;
}

.light .moon-box {
    height: 0;
}

.light .bg {
    background-color: #ffeea2;
}

.dark .sun-box {
    height: 0;
}

.dark .moon-box {
    height: 100%;
}

.dark .bg {
    background-color: #040720;
}

.btn-box {
    position: absolute;
    top: 5px;
    right: 100px;
    z-index: 999;
    display: flex;
}

.btn-box div {
    width: 90px;
    height: 40px;
    background: rgba(255, 255, 255, 0.7);
    margin: 5px;
    line-height: 40px;
    text-align: center;
    font-size: 14px;
    border-radius: 5px;
    cursor: pointer;
}

.btn-box div:hover {
    background: #fff;
}